Methods and apparatuses for frequency hopping of sounding reference signals in partial bandwidths

ABSTRACT

In some scenarios, SRS transmission over the full SRS bandwidth may be unnecessary and/or inefficient. Therefore, a need exists for approaches to SRS transmission over less than the full SRS bandwidth. Described herein are techniques and solutions of SRS transmission using only a portion of the full SRS bandwidth, or a partial SRS bandwidth. The present disclosure provides for SRS transmission using a partial SRS bandwidth through sounding patterns that use only the partial SRS bandwidth and/or using a partial SRS bandwidth through various SRS sequence generation configured for the partial SRS bandwidth. An apparatus receives an SRS configuration indicating a full SRS bandwidth; determines a frequency hopping pattern for SRS transmission based on the SRS configuration, and the frequency hopping pattern is limited to a partial SRS bandwidth less than the full SRS bandwidth; and transmits the SRS transmission to the base station based on the frequency hopping pattern.

BACKGROUND Technical Field

The present disclosure generally relates to communication systems, andmore particularly, to reference signals transmitted from a userequipment to a base station within a certain bandwidth.

INTRODUCTION

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. 5G NR includes services associated with enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), andultra-reliable low latency communications (URLLC). Some aspects of 5G NRmay be based on the 4G Long Term Evolution (LTE) standard. There existsa need for further improvements in 5G NR technology. These improvementsmay also be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In access networks of some example radio access technologies (RATs),such as a 5G New Radio (NR) access network, a base station may estimateat least one channel on which transmissions are received from a userequipment (UE) (e.g., an uplink channel) using at least one soundingreference signal (SRS). Additionally or alternatively, SRS can be usedfor uplink frequency selective scheduling and/or uplink timingestimation. Accordingly, the UE transmits the at least one SRS to thebase station, although the UE may transmit SRS over a wider bandwidththan an uplink channel. In so doing, the UE may sound all ports of anSRS resource in each symbol of the SRS resource.

When a UE transmits SRS, a full bandwidth may be available for the SRStransmission. However, a full SRS bandwidth may be an entire bandwidthof interest, but less than an entire system bandwidth (although thebandwidth of interest potentially may be equal to the system bandwidth).In some aspects, then, a full SRS bandwidth may be configured by a basestation for the UE.

Potentially, the UE may be configured to use frequency hopping for SRS.For example, the UE may have insufficient transmission power to soundover the full SRS bandwidth (e.g., when the UE is near a cell edge), andtherefore, the base station may configure the UE to use frequencyhopping for SRS. When using frequency hopping, however, the UE may stilltransmit SRS over the full SRS bandwidth, but may do so over multiplesymbols (e.g., multiple adjacent symbols).

In some scenarios, SRS transmission over the full SRS bandwidth may beunnecessary and/or inefficient (e.g., in terms of power overhead).Therefore, a need exists for approaches to SRS transmission over lessthan the full SRS bandwidth.

The present disclosure describes various techniques and solutions of SRStransmission using only a portion of the full SRS bandwidth, or apartial SRS bandwidth. Such techniques and solutions of SRS transmissionusing a partial SRS bandwidth may allow for UE multiplexing so that agreater number of UEs are able to transmit SRS in a cell. Additionally,SRS transmission using a partial SRS bandwidth may reduce some poweroverhead incurred by the UE from SRS transmission.

In some aspects, the present disclosure provides for SRS transmissionusing a partial SRS bandwidth through sounding patterns (e.g., frequencyhopping patterns) that use only the partial SRS bandwidth. In some otheraspects, the present disclosure provides for SRS transmission using apartial SRS bandwidth through various SRS sequence generation configuredfor the partial SRS bandwidth.

In one aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a UE. The apparatusis configured to receive, from a base station, an SRS configurationindicating a full SRS bandwidth. The apparatus is further configured todetermine a frequency hopping pattern for SRS transmission based on theSRS configuration, and the frequency hopping pattern may be limited to apartial SRS bandwidth that is less than the full SRS bandwidth. Inaddition, the apparatus is configured to transmit the SRS transmissionto the base station based on the frequency hopping pattern.

In another aspect of the disclosure, another method, anothercomputer-readable medium, and another apparatus are provided. The otherapparatus may be a base station. The other apparatus is configured totransmit, to a UE, an SRS configuration indicating a full SRS bandwidth.The other apparatus is further configured to receive, from the UE, anSRS transmission according to a frequency hopping pattern based on theSRS configuration, and the frequency hopping pattern is limited to apartial SRS bandwidth less than the full SRS bandwidth.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIG. 2A is a diagram illustrating an example of a first frame, inaccordance with various aspects of the present disclosure.

FIG. 2B is a diagram illustrating an example of DL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 2C is a diagram illustrating an example of a second frame, inaccordance with various aspects of the present disclosure.

FIG. 2D is a diagram illustrating an example of UL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 is a diagram illustrating example configurations for transmissionof a sounding reference signal (SRS).

FIG. 5 is a diagram illustrating example resource mappings of SRSresources.

FIG. 6 is a call flow diagram illustrating example operations for SRStransmissions by UEs to a base station.

FIG. 7 is a diagram illustrating an example frequency hopping patternfor an SRS resource over a full bandwidth configured for SRS.

FIG. 8 is a diagram illustrating example frequency hopping patterns forSRS transmission over a partial bandwidth of a full bandwidth configuredfor SRS.

FIG. 9 is a diagram illustrating other example frequency hoppingpatterns for SRS transmission over a partial bandwidth of a fullbandwidth configured for SRS.

FIG. 10 is a diagram illustrating further example frequency hoppingpatterns for SRS transmission over a partial bandwidth of a fullbandwidth configured for SRS.

FIG. 11 is a flowchart of a method of wireless communication by a UE.

FIG. 12 is a flowchart of a method of wireless communication by a basestation.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, user equipment(s) (UE) 104, an Evolved Packet Core (EPC)160, and another core network 190 (e.g., a 5G Core (5GC)). The basestations 102 may include macrocells (high power cellular base station)and/or small cells (low power cellular base station). The macrocellsinclude base stations. The small cells include femtocells, picocells,and microcells.

The base stations 102 configured for 4G Long Term Evolution (LTE)(collectively referred to as Evolved Universal Mobile TelecommunicationsSystem (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interfacewith the EPC 160 through first backhaul links 132 (e.g., S1 interface).The base stations 102 configured for 5G New Radio (NR) (collectivelyreferred to as Next Generation RAN (NG-RAN)) may interface with corenetwork 190 through second backhaul links 184. In addition to otherfunctions, the base stations 102 may perform one or more of thefollowing functions: transfer of user data, radio channel ciphering anddeciphering, integrity protection, header compression, mobility controlfunctions (e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, radio access network (RAN) sharing, MultimediaBroadcast Multicast Service (MBMS), subscriber and equipment trace, RANinformation management (RIM), paging, positioning, and delivery ofwarning messages. The base stations 102 may communicate directly orindirectly (e.g., through the EPC 160 or core network 190) with eachother over third backhaul links 134 (e.g., X2 interface). The firstbackhaul links 132, the second backhaul links 184, and the thirdbackhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y megahertz (MHz) (e.g., 5, 10, 15, 20, 100, 400,etc. MHz) bandwidth per carrier allocated in a carrier aggregation of upto a total of Yx MHz (x component carriers) used for transmission ineach direction. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the Institute of Electrical and Electronics Engineers(IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154, e.g., in a 5 gigahertz (GHz) unlicensedfrequency spectrum or the like. When communicating in an unlicensedfrequency spectrum, the STAs 152/AP 150 may perform a clear channelassessment (CCA) prior to communicating in order to determine whetherthe channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same unlicensed frequencyspectrum (e.g., 5 GHz, or the like) as used by the Wi-Fi AP 150. Thesmall cell 102′, employing NR in an unlicensed frequency spectrum, mayboost coverage to and/or increase capacity of the access network.

The electromagnetic spectrum is often subdivided, based onfrequency/wavelength, into various classes, bands, channels, etc. In 5GNR, two initial operating bands have been identified as frequency rangedesignations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). Thefrequencies between FR1 and FR2 are often referred to as mid-bandfrequencies. Although a portion of FR1 is greater than 6 GHz, FR1 isoften referred to (interchangeably) as a “sub-6 GHz” band in variousdocuments and articles. A similar nomenclature issue sometimes occurswith regard to FR2, which is often referred to (interchangeably) as a“millimeter wave” band in documents and articles, despite beingdifferent from the extremely high frequency (EHF) band (30 GHz-300 GHz)which is identified by the International Telecommunications Union (ITU)as a “millimeter wave” band.

With the above aspects in mind, unless specifically stated otherwise, itshould be understood that the term “sub-6 GHz” or the like if usedherein may broadly represent frequencies that may be less than 6 GHz,may be within FR1, or may include mid-band frequencies. Further, unlessspecifically stated otherwise, it should be understood that the term“millimeter wave” or the like if used herein may broadly representfrequencies that may include mid-band frequencies, may be within FR2, ormay be within the EHF band.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include and/or be referred to as an eNB, gNodeB(gNB), or another type of base station. Some base stations, such as gNB180 may operate in a traditional sub 6 GHz spectrum, in millimeter wavefrequencies, and/or near millimeter wave frequencies in communicationwith the UE 104. When the gNB 180 operates in millimeter wave or nearmillimeter wave frequencies, the gNB 180 may be referred to as amillimeter wave base station. The millimeter wave base station 180 mayutilize beamforming 182 with the UE 104 to compensate for the path lossand short range. The base station 180 and the UE 104 may each include aplurality of antennas, such as antenna elements, antenna panels, and/orantenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a MBMS Gateway 168, a BroadcastMulticast Service Center (BM-SC) 170, and a Packet Data Network (PDN)Gateway 172. The MME 162 may be in communication with a Home SubscriberServer (HSS) 174. The MME 162 is the control node that processes thesignaling between the UEs 104 and the EPC 160. Generally, the MME 162provides bearer and connection management. All user Internet protocol(IP) packets are transferred through the Serving Gateway 166, whichitself is connected to the PDN Gateway 172. The PDN Gateway 172 providesUE IP address allocation as well as other functions. The PDN Gateway 172and the BM-SC 170 are connected to the IP Services 176. The IP Services176 may include the Internet, an intranet, an IP Multimedia Subsystem(IMS), a PS Streaming Service, and/or other IP services. The BM-SC 170may provide functions for MBMS user service provisioning and delivery.The BM-SC 170 may serve as an entry point for content provider MBMStransmission, may be used to authorize and initiate MBMS Bearer Serviceswithin a public land mobile network (PLMN), and may be used to scheduleMBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMStraffic to the base stations 102 belonging to a Multicast BroadcastSingle Frequency Network (MBSFN) area broadcasting a particular service,and may be responsible for session management (start/stop) and forcollecting eMBMS related charging information.

The core network 190 may include a Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides Quality of Service(QoS) flow and session management. All user Internet protocol (IP)packets are transferred through the UPF 195. The UPF 195 provides UE IPaddress allocation as well as other functions. The UPF 195 is connectedto the IP Services 197. The IP Services 197 may include the Internet, anintranet, an IMS, a Packet Switch (PS) Streaming Service, and/or otherIP services.

The base station may include and/or be referred to as a gNB, Node B,eNB, an access point, a base transceiver station, a radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), a transmit reception point (TRP), or someother suitable terminology. The base station 102 provides an accesspoint to the EPC 160 or core network 190 for a UE 104. Examples of UEs104 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heartmonitor, etc.). The UE 104 may also be referred to as a station, amobile station, a subscriber station, a mobile unit, a subscriber unit,a wireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology.

Although the present disclosure may focus on 5G NR, the concepts andvarious aspects described herein may be applicable to other similarareas, such as LTE, LTE-Advanced (LTE-A), Code Division Multiple Access(CDMA), Global System for Mobile communications (GSM), or otherwireless/radio access technologies.

Referring again to FIG. 1 , in certain aspects, the base station 102/180may be configured to transmit, to the UE 104, a sounding referencesignal (SRS) configuration indicating a full SRS bandwidth. The full SRSbandwidth may be a bandwidth of interest over which the UE 104communicates with the base station 102/180, and therefore, the full SRSbandwidth may be less than the entire system bandwidth (although thefull SRS bandwidth potentially may be equal to the entire systembandwidth). The base station 102/180 may be configured to receive, fromthe UE 104 and based on the SRS configuration, an SRS transmissionaccording to a frequency hopping pattern that is limited to a partialSRS bandwidth less than the full SRS bandwidth (198).

Correspondingly, the UE 104 may be configured to receive, from the basestation 102/180, the SRS configuration indicating the full SRSbandwidth. The UE 104 may be further configured to determine, based onthe SRS configuration, the frequency hopping pattern for SRStransmission that is limited to the partial SRS bandwidth less than thefull SRS bandwidth. Accordingly, the UE 104 may transmit, to the basestation 102/180, the SRS transmission based on the frequency hoppingpattern that is limited to the partial SRS bandwidth less than the fullSRS bandwidth (198).

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The 5G NR frame structure may befrequency division duplexed (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplexed (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and F isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

Other wireless communication technologies may have a different framestructure and/or different channels. A frame, e.g., of 10 milliseconds(ms), may be divided into 10 equally sized subframes (1 ms). Eachsubframe may include one or more time slots. Subframes may also includemini-slots, which may include 7, 4, or 2 symbols. Each slot may include7 or 14 symbols, depending on the slot configuration. For slotconfiguration 0, each slot may include 14 symbols, and for slotconfiguration 1, each slot may include 7 symbols. The symbols on DL maybe cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM)(CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for highthroughput scenarios) or discrete Fourier transform (DFT) spread OFDM(DFT-s-OFDM) symbols (also referred to as single carrierfrequency-division multiple access (SC-FDMA) symbols) (for power limitedscenarios; limited to a single stream transmission). The number of slotswithin a subframe is based on the slot configuration and the numerology.For slot configuration 0, different numerologies μ 0 to 4 allow for 1,2, 4, 8, and 16 slots, respectively, per subframe. For slotconfiguration 1, different numerologies 0 to 2 allow for 2, 4, and 8slots, respectively, per subframe. Accordingly, for slot configuration 0and numerology μ, there are 14 symbols/slot and 2^(μ) slots/subframe.The subcarrier spacing and symbol length/duration are a function of thenumerology. The subcarrier spacing may be equal to 2^(μ)*15 kilohertz(kHz), where μ is the numerology 0 to 4. As such, the numerology μ=0 hasa subcarrier spacing of 15 kHz and the numerology μ=4 has a subcarrierspacing of 240 kHz. The symbol length/duration is inversely related tothe subcarrier spacing. FIGS. 2A-2D provide an example of slotconfiguration 0 with 14 symbols per slot and numerology μ=2 with 4 slotsper subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60kHz, and the symbol duration is approximately 16.67 μs. Within a set offrames, there may be one or more different bandwidth parts (BWPs) (seeFIG. 2B) that are frequency division multiplexed. Each BWP may have aparticular numerology.

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as R_(x) for one particular configuration, where 100× is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A PDCCH within one BWP may be referred to as a controlresource set (CORESET). Additional BWPs may be located at greater and/orlower frequencies across the channel bandwidth. A primarysynchronization signal (PSS) may be within symbol 2 of particularsubframes of a frame. The PSS is used by a UE 104 to determinesubframe/symbol timing and a physical layer identity. A secondarysynchronization signal (SSS) may be within symbol 4 of particularsubframes of a frame. The SSS is used by a UE to determine a physicallayer cell identity group number and radio frame timing. Based on thephysical layer identity and the physical layer cell identity groupnumber, the UE can determine a physical cell identifier (PCI). Based onthe PCI, the UE can determine the locations of the aforementioned DM-RS.The physical broadcast channel (PBCH), which carries a masterinformation block (MIB), may be logically grouped with the PSS and SSSto form a synchronization signal (SS)/PBCH block (also referred to as SSblock (SSB)). The MIB provides a number of RBs in the system bandwidthand a system frame number (SFN). The physical downlink shared channel(PDSCH) carries user data, broadcast system information not transmittedthrough the PBCH such as system information blocks (SIBs), and pagingmessages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. The UE may transmit SRS. The SRS may betransmitted in the last symbol of a subframe. The SRS may have a combstructure, and a UE may transmit SRS on one of the combs. The SRS may beused by a base station for channel quality estimation to enablefrequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARQ) acknowledgement (ACK)/non-acknowledgement (NACK)feedback. The PUSCH carries data, and may additionally be used to carrya buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

In some aspects, at least one of the TX processor 368, the RX processor356, and/or the controller/processor 359 may be configured to performaspects in connection with (198) of FIG. 1 .

In some other aspects, at least one of the TX processor 316, the RXprocessor 370, and/or the controller/processor 375 may be configured toperform aspects in connection with (198) of FIG. 1 .

FIG. 4 is a diagram 400 of example configurations of SRS resources. Inan access network of an example RAT, such as a 5G NR access network, abase station may estimate at least one channel on which transmissionsare received from a UE (e.g., an uplink channel) using at least one SRS,which may be referred to as an SRS resource (although an SRS resourcedoes not necessarily correspond to only one subcarrier over one symbolor an RE). Additionally or alternatively, SRS can be used for uplinkfrequency selective scheduling and/or uplink timing estimation.Accordingly, the UE transmits the at least one SRS to the base station(see, e.g., FIGS. 2C-2D, supra), although potentially over a widerbandwidth than an uplink channel. The UE may sound all ports of an SRSresource in each symbol of the SRS resource.

According to various aspects, a slot 402 may be configured to includeSRS on a set of RBs spanning an entire bandwidth of interest for a basestation and a UE. Potentially, the entire bandwidth of interest may bean uplink bandwidth of interest. The bandwidth of interest may be lessthan an entire system bandwidth; although the bandwidth of interestpotentially may be equal to the entire system bandwidth. For example,the bandwidth of interest may be 36, 48, or 64 RBs (although differentnumbers of RBs are also possible for different bandwidths of interest).In some aspects, a UE may be configured to transmit SRS on the entirebandwidth of interest. Thus, the entire bandwidth of interest may alsobe referred to in the present disclosure as a “full SRS bandwidth.”

A base station may configure the entire bandwidth of interest, andtherefore, the base station may signal the full SRS bandwidth to a UE,e.g., as part of an SRS configuration. In some aspects, the base stationmay signal the full SRS bandwidth and/or other information associatedwith SRS configuration to the UE via RRC signaling. In some otheraspects, the base station may signal the full SRS bandwidth and/or otherSRS configuration information using DCI (e.g., information included inDCI and/or a DCI Format) and/or a MAC control element (CE).

In the time domain, the slot 402 may be configured to support SRSresources that span a certain number of symbols, which may be adjacent(e.g., 1, 2, or 4 adjacent symbols) with up to 4 ports per SRS resource.According to some aspects, an SRS may only be transmitted in the last 6symbols of the slot 402 (e.g., 5G NR Release 15 and Release 16 maysupport SRS transmission in the last 6 symbols of a slot). According tosome other aspects, however, an SRS may be transmitted in any symbols ofa slot (e.g., 5G NR Release 17 and beyond potentially may support SRStransmission in more or all symbols of the slot 402).

Additionally or alternatively, the SRS may only be transmitted in a slotafter uplink data of that slot, such as uplink data carried on a PUSCH.For example, a PUSCH may be mapped to a subset of the symbols 0 through13 of the slot 402. Next, the SRS may be mapped to a subset of theremaining symbols 8 through 13 of the slot 402—e.g., the SRS may bemapped to 1, 2, or 4 adjacent symbols within symbols 8 through 13 of theslot 402.

When a UE transmits SRS resources, the SRS resources may be included inan SRS resource set of that UE, such as SRS resource set 1 410 a or SRSresource set 2 410 b. An SRS resource set may be configured to includeone SRS resource or a group of multiple SRS resources, with the SRSresource(s) included therein being based on the use case for which theSRS is transmitted, such antenna switching, codebook-based,non-codebook-based, beam management, and the like. Further, a UE may beconfigured for aperiodic, semi-persistent, or periodic transmission ofan SRS resource set, e.g., with aperiodic transmission of an SRSresource set being signaled from the base station to the UE via DCI.

Illustratively, for SRS antenna switching use cases, 1 or 2 TX to 2 or 4RX antenna switching may be supported, which may be denoted as “1T2R,”“2T4R,” “1T4R,” and “1T4R/2T4R” where a UE supports both 1 TX to 4 RXand 2 TX to 4 RX antenna switching (however, antenna switching in whichthe numbers of TX and RX are equal may also be supported). To supportantenna switching, an SRS resource set is configured with two (for 1T2Ror 2T4R) or four (for 1T4R) SRS resources transmitted in differentsymbols. Each SRS resource includes one (for 1T2R or 1T4R) or two (for2T4R) antenna port(s), and the SRS port(s) of each SRS resource isassociated with different UE antenna port(s).

As shown in one example of FIG. 4 , the SRS resource set 1 410 a isbased on 1T4R, and therefore includes four SRS resources 1 through 4 412a-d. The four SRS resources 1 through 4 412 a-d may occur in one slot,such as within four adjacent symbols of symbols 8 through 13 of the slot402. However, other configurations may also be supported. For example,for 1T4R, two aperiodic SRS resource sets with a total of four SRSresources transmitted in different symbols of two different slots may beconfigured, instead of SRS resources 1 through 4 412 a-d in one slot.

As shown in another example of FIG. 4 , the SRS resource set 2 410 b maybe based on a use case of codebook-based transmission (e.g., forbeamforming), such as when feedback of precoding information (e.g., PMI)and/or other information is configured to increase throughput at thereceiver side (e.g., base station). The SRS resource set 2 410 b mayinclude one SRS resource 5 412 e based on codebook-based transmission.The SRS resource 5 412 e may be transmitted in a single symbol (e.g.,one of symbols 8 through 13 of the slot 402), and therefore, the SRSresource 5 412 e may be wideband in that the SRS resource 5 412 e mayspan the full SRS bandwidth.

FIG. 5 is a diagram 500 of example frequency hopping for SRStransmission. As described, supra, an SRS resource set may span a fullSRS bandwidth. For example, one SRS resource may span the full SRSbandwidth so that the full SRS bandwidth may be sounded over one symbol.However, an SRS resource set may not span the full SRS bandwidth insymbol; rather, the SRS resource set may include one or more SRSresources that span the full SRS bandwidth over multiple symbols.

To that end, a UE may be configured to use frequency hopping for an SRSresource set. For example, the UE may have insufficient transmissionpower to sound over the full SRS bandwidth (e.g., when the UE is near acell edge), and therefore, a base station may configure the UE to usefrequency hopping for SRS transmission. When using frequency hopping,however, the UE may still transmit SRS over the full SRS bandwidth, butmay do so over multiple symbols (e.g., multiple adjacent symbols).

According to the examples shown in FIG. 5 , a full SRS bandwidth (orsounding bandwidth) may be configured to be 48 PRBs. A UE may sound overthe full SRS bandwidth according to different SRS frequency hoppingpatterns 502, 522, 542. An SRS resource may be transmitted at each hop,with each hop spanning a fractional amount of the full SRS bandwidth(e.g., one half or one quarter of the full SRS bandwidth) over onesymbol.

For example, in the first SRS frequency hopping pattern 502, SRSresource 504 may be transmitted over two adjacent symbols 12 and 13 ofat least one slot. Each of the SRS resource 504 may span 24 PRBs of adifferent half of the full SRS bandwidth so that all 48 PRBs of the fullSRS bandwidth are sounded over two adjacent symbols.

In the example of the second SRS frequency hopping pattern 522, SRSresource 504 may be transmitted over four adjacent symbols 10 through 13of at least one slot. The SRS resources 504 may span 12 PRBs of adifferent quarter of the full SRS bandwidth so that all 48 PRBs of thefull SRS bandwidth are sounded over four adjacent symbols.

In the example of the third SRS frequency hopping pattern 542, SRSresource 504 may be transmitted over four adjacent symbols 10 through 13of at least one slot. SRS resource 504 may span 24 PRBs of the full SRSbandwidth. Different from the first two SRS frequency hopping patterns502, 522, however, the SRS resource may be repeating. For example, SRSresource 504 may repeat over symbols 10 and 11, and SRS resource 504 mayrepeat over symbols 12 and 13. Such repetition may increase theeffectiveness of sounding over each 24 PRB bandwidth, e.g., relative tosounding each half or quarter of the 48 PRB bandwidth only once persymbol.

In some scenarios, transmission of SRS resource sets that span the fullSRS bandwidth may be unnecessary and/or inefficient (e.g., in terms ofpower overhead). For example, sounding over only a portion of the fullSRS bandwidth may be sufficient for some channel estimation, uplinktiming alignment, and/or uplink frequency selective scheduling by a basestation. Additionally or alternatively, a UE may operate within powerconstraints that prevent the UE from sounding the full SRS bandwidth,such as when a UE has an insufficient amount of remaining battery chargeor when a UE is configured as a low-power device capable of achievingcomparatively lower transmission power than other UEs. In still otherexamples, a base station may provide a cell in which the number oftransmitting UEs exceeds the uplink resources available for SRStransmission without some additional mechanism for multiplexing.Therefore, a need exists for approaches to SRS transmission over lessthan the full SRS bandwidth.

The present disclosure, and FIGS. 6-12 in particular, describes varioustechniques and solutions of SRS transmission using only a portion of thefull SRS bandwidth, or a partial SRS bandwidth. Such techniques andsolutions of SRS transmission using a partial SRS bandwidth may allowfor UE multiplexing so that a greater number of UEs are able to transmitSRS in a cell. Furthermore, SRS transmission using a partial SRSbandwidth may reduce some power overhead, such as that incurred by UEsfrom SRS transmission and/or base stations from SRS reception.

In FIGS. 6-12 , some techniques and solutions of SRS transmission usinga partial SRS bandwidth are provided through sounding patterns (e.g.,frequency hopping patterns) that use only a partial SRS bandwidth, whichmay be a fractional amount of a full SRS bandwidth. Some other solutionsof SRS transmission using a partial SRS bandwidth are provided in FIGS.6-12 through generation of various SRS sequences configured for use witha partial SRS bandwidth that is less than the full SRS bandwidth.

With reference to FIG. 6 , a call flow diagram 600 illustrates variousoperations for SRS transmission using a partial SRS bandwidth that isless than a full SRS bandwidth. In FIG. 6 , a base station 602 may beconfigured to provide a cell on which multiple UEs 604 a-b operate. Forexample, referring to FIGS. 1 and 3 , the base station 602 may beimplemented as a base station 102/180, 310, and each of the UEs a-b maybe implemented as a UE 104, 350.

Each of the UEs 604 a-b may be configured to transmit data and/orcontrol information to the base station 602. Transmission in suchdirection may be regarded as uplink. Uplink data may be carried on anuplink data channel, such as a PUSCH. The base station 602 may configurePUSCH transmission for each of the UEs 604 a-b on a respective activeBWP, which may be updated by the base station 602.

To increase the accuracy and success of decoding uplink data receivedfrom the UEs 604 a-b, the base station 602 may perform channelestimation, e.g., in order to model current channel conditions forreliably receiving uplink data from the UEs 604 a-b with a high datarate. The channel estimation may be performed over an entire bandwidthof interest, which may be greater than any one active BWP (e.g., theentire bandwidth of interest for the UEs 604 a-b may be the entirebandwidth spanned by all BWPs that potentially may be activated by thebase station 602 for the UEs 604 a-b).

Each of the UEs 604 a-b may be able to sound over a bandwidth bytransmitting an SRS resource set including one or more SRS resources.For example, each of the UEs 604 a-b may sound all SRS ports in one ormore symbols of an SRS resource set. In some aspects, at least one ofthe UEs 604 a-b may sound over the entire bandwidth of interest, or fullSRS bandwidth, by transmitting an SRS resource set including one or moreSRS resources that span the full SRS bandwidth in the aggregate. In someother aspects, however, at least one of the UEs 604 a-b may sound over afractional amount of the entire bandwidth of interest, or a partial SRSbandwidth that is less than the full SRS bandwidth, by transmitting anSRS resource set including one or more SRS resources that span thepartial SRS bandwidth and not the full SRS bandwidth.

The base station 602 may configure the UEs 604 a-b for sounding bytransmitting SRS configuration information 622 a-b to the UEs 604 a-b.In some aspects, each of the SRS configuration information 622 a-b maybe individually configured for each of the UEs 604 a-b. Thus, the basestation 602 may transmit, to the first UE 604 a, first SRS configurationinformation 622 a that is different from second SRS configurationinformation 622 b transmitted by the base station 602 to the second UE604 b.

According to various aspects, each of the SRS configuration information622 a-b may include and/or indicate any information associated with SRStransmission. Each of the SRS configuration information 622 a-b may betransmitted in one or more messages that may be signaled in the same ordifferent type or format, such as RRC signaling, DCI, and/or MAC CE. Forexample, the base station 602 may signal the first SRS configurationinformation 622 a to the first UE 604 a using RRC signaling, DCI, and aMAC CE at respective times such that a first portion of the first SRSconfiguration information 622 a is signaled via RRC signaling at time t,a second portion of the first SRS configuration information 622 a issignaled via DCI at time t+x, and a third portion of the first SRSconfiguration information 622 a is signaled via MAC CE at time t+y.

The base station 602 may configure an entire bandwidth of interest, alsoreferred to as a “full SRS bandwidth,” for each of the UEs 604 a-b. Thebase station 602 may transmit information indicating a full SRSbandwidth to each of the UEs 604 a-b in a respective one of the firstand second SRS configuration information 622 a-b. For example, the basestation 602 may indicate the full SRS bandwidth via RRC signaling;although the full SRS bandwidth may be configured via DCI or MAC CEaccording to other aspects.

In either the same or a different message, the base station 602 mayinclude, in at least one of the SRS configuration information 622 a-b, aperiodicity or duration for SRS transmission. The periodicity (orduration) may indicate whether SRS transmission is periodic oraperiodic, or potentially semi-persistent.

In some aspects, the SRS transmission periodicity may be configured viaRRC signaling as aperiodic, but the base station 602 may activate SRStransmission from one of the UEs 604 a-b via DCI. In some other aspects,the SRS transmission periodicity may be configured via RRC signaling asperiodic, and such RRC signaling may further configure a number of msfor the periodicity, as well as a subframe offset for the periodicity.

Additionally, the base station 602 may include, in at least one of theSRS configuration information 622 a-b, a frequency domain position thatdefines the starting position of SRS transmission in the frequencydomain. For example, the frequency domain position (e.g., labeledfreqDomainPosition) may have a value for an index of the lowest RB (orPRB) to be spanned by SRS transmission.

As described with respect to FIG. 2C, supra, SRS transmission may notoccur on every subcarrier of an RB (or PRB). Rather, an SRS resource maybe mapped to every other subcarrier of an RB in a transmission combstructure, starting either with the first (e.g., lowest) subcarrier orthe second (e.g., next consecutive following the lowest) subcarrier.

Thus, the base station 602 may include, in at least one of the SRSconfiguration information 622 a-b, a value for transmission comb (e.g.,labeled transmissionComb). The transmission comb value may configure oneof the UEs 604 a-b to transmit on every even subcarrier (e.g.,transmission comb 0 starting with subcarrier index 0) or every oddsubcarrier (e.g., transmission comb 1 starting with subcarrier index 1).

To preserve orthogonality, the base station 602 may include, in at leastone of the SRS configuration information 622 a-b, a value for a cyclicshift to be applied by one of the UEs 604 a-b for SRS transmission. Forexample, the cyclic shift value (e.g., labeled cyclicShift) may includea value inclusively between 1 and 8 (although more, fewer, or differentvalues are also possible). Illustratively, when UEs 604 a-b share thesame full SRS bandwidth according to SRS configuration information 622a-b, SRS transmissions of the UEs 604 a-b may be multiplexed in the fullSRS bandwidth because respective different cyclic shifts will maintainorthogonality.

According to some aspects, the base station 602 may include, in at leastone of the SRS configuration information 622 a-b, a bandwidth of SRSresource(s) of an SRS resource set. For example, the SRS resourcebandwidth (e.g., labeled srs-Bandwidth) may indicate a number of RBs (orPRBs) to be spanned by each of the one or more SRS resource(s)configured to be included in an SRS resource set of at least one of theUE 604 a-b.

Relatedly, the base station 602 may include, in at least one of the SRSconfiguration information 622 a-b, information configuring a hoppingbandwidth for SRS transmission (e.g., labeled srs-HoppingBandwidth).That is, the SRS hopping bandwidth may be a number of consecutive RBs(or PRBs), starting from the frequency domain position, that span theentire bandwidth of interest. Thus, in some aspects, the SRS hoppingbandwidth may be equal to the full SRS bandwidth.

At least one of the SRS configuration information 622 a-b may include arespective value for each of the SRS resource bandwidth and the SRShopping bandwidth. The respective values may implicitly indicate arespective number of RBs (or PRBs) to be spanned by each of the SRSresource bandwidth and the SRS hopping bandwidth. For example, each ofthe respective values may be associated with a respective table (e.g., alookup table) or similar keyed or indexed data structure, which may be(pre-)configured in at least one of the UEs 604 a-b.

Each of the respective values may correspond to a row, column, or otherentry of the associated table, and the number of RBs (or PRBs)configured for the SRS resource bandwidth or the SRS hopping bandwidthmay be explicitly or implicitly included in the row, column, or otherentry corresponding to the respective value indicated in the at leastone of the SRS configuration information 622 a-b.

By way of illustration, the first SRS configuration information 622 amay include a value for the SRS resource bandwidth of bw3, and further,may include a value for the SRS hopping bandwidth of hbw0. The first UE604 a may identify a row, column, or other entry of at least one tablethat corresponds to bw3, and may derive a number of RBs (or PRBs)configured to be spanned by each SRS resource from the correspondingrow, column, or other entry—e.g., the SRS resource bandwidth may beequal to 4. Similarly, the first UE 604 a may identify a row, column, orother entry of at least one table that corresponds to hbw0, and mayderive a number of RBs (or PRBs) configured all the bandwidth ofinterest—e.g., the full SRS bandwidth—from the corresponding row,column, or other entry—e.g., the SRS hopping bandwidth may be equal to48.

According to some aspects, at least one of the UEs 604 a-b may determinewhether SRS frequency hopping is enabled or disabled based oninformation implicitly signaling in a respective one of the SRSconfiguration information 622 a-b. Specifically, at least one of the UE604 a-b may derive an enabled or disabled state of SRS frequency hoppingfrom a combination of the respective values configured for the SRSresource bandwidth and the SRS hopping bandwidth.

For example, when at least one of the SRS configuration information 622a-b includes a value of the SRS hopping bandwidth (e.g., hbw0, hbw1,hbw2, or hbw3) configured to be less than a value of the SRS resourcebandwidth (e.g., bw0, bw1, bw2, or bw3), then SRS frequency hopping maybe enabled. However, when at least one of the SRS configurationinformation 622 a-b includes a value of the SRS hopping bandwidth (e.g.,hbw0, hbw1, hbw2, or hbw3) configured to be greater than or equal to avalue of the SRS resource bandwidth (e.g., bw0, bw1, bw2, or bw3), thenSRS frequency hopping may be disabled. Thus, as shown in the foregoingillustration, SRS frequency hopping is enabled for the first UE 604 abecause the SRS resource bandwidth of bw3 is greater than the SRShopping bandwidth of hbw0. In effect, then, the first UE 604 a may use 4RBs configured for each SRS resource (e.g., symbol) for frequencyhopping over the 48 RBs bandwidth configured for the SRS hoppingbandwidth (e.g., the full SRS bandwidth).

In some aspects, at least one of the UEs 604 a-b may be configured forSRS frequency hopping over the full SRS bandwidth. For example, thesecond UE 604 b may be configured for SRS frequency hopping over thefull SRS bandwidth. Therefore, SRS resource(s) of an SRS resource setconfigured for the second UE 604 b may span the full SRS bandwidth overone or more symbols.

Referring to FIG. 7 , for example, a diagram 700 illustrates a full SRSbandwidth frequency hopping pattern 702. By way of illustration, thefull SRS bandwidth may be configured to span 16× RBs (e.g., with 12subcarriers per RB). In one example aspect, x may be equal to 4 RBs, andtherefore, the full SRS bandwidth may be equal to 64 RBs (e.g., 768subcarriers with 12 subcarriers per RB). However, x may be differentfrom (e.g., greater than) 4 in some other aspects.

The second UE 604 b may be configured with SRS resource 704. The SRSbandwidth for the second UE 604 b may be equal to 16 RBs, and the SRShopping bandwidth may be equal to 64 RBs. Thus, the second UE 604 b maytransmit SRS resource 704 on a respective (unique) 16 RB bandwidth overa respective one of symbol indices 10 through 13, and so the second UE604 b may sound over the full 64 RB bandwidth.

In order for SRS resource 704 to span a respective portion of the fullSRS bandwidth, an SRS frequency hopping pattern for the full SRSbandwidth may be configured. The SRS frequency hopping pattern maydefine a respective hopping bandwidth (e.g., a set of contiguous RBs)for each hop, with each hop occurring at a respective symbol of at leastone slot.

In the context of FIG. 7 , for example, a full SRS bandwidth frequencyhopping pattern may define a unique 16 RB bandwidth for each hop at arespective one of symbols 10 through 13 (e.g., assuming x=4).Accordingly, the second UE 604 b transmits SRS on the first 16 RBs ofthe full SRS bandwidth at the first hop for symbol 10. At the next hopover symbol 11, the second UE 604 b transmits SRS on 16 RBs startingafter the first 32 RBs of the full SRS bandwidth (e.g., from subcarrierindex 383 to subcarrier index 575, with subcarrier indices from 0, 1, 2,. . . , 765, 766, 768 for x=4 RBs). At the third hop over symbol 12, thesecond UE 604 b transmits SRS on 16 RBs starting after the first 16 RBsof the full SRS bandwidth and ending with the 32^(nd) RB. At the finalhop over symbol 13, the second UE 604 b transmits SRS on 16 RBs startingafter the first 48 RBs and ending with the last (64^(th)) RB of the fullSRS bandwidth. Thus, the full SRS bandwidth is sounded by the SRSresource 704, as the SRS resource 704 spans all RBs of the full SRSbandwidth over four symbol hops occurring at symbols 10 through 13.

Referring again to FIG. 6 , at least one of the UEs 604 a-b may beconfigured to use an SRS frequency hopping pattern that only uses aportion of the full SRS bandwidth—that is, a partial SRS bandwidth thatis less than the full SRS bandwidth. In effect, at least one of the UEs604 a-b may be configured with SRS resource(s) of an SRS resource setthat spans the partial SRS bandwidth but not the full SRS bandwidth.Sounding over the partial SRS bandwidth that is less than the full SRSbandwidth may be more efficient (e.g., in terms of power overhead and/orUE capacity), while still being sufficient for channel estimation,uplink frequency selective scheduling, uplink timing estimation, and soforth by the base station 602.

In order to transmit SRS resources, however, the UEs 604 a-b maygenerate 624, 626 SRS sequences. In some aspects, SRS sequencegeneration may be based on the SRS configuration information. Forexample, the first UE 604 a may generate 624 an SRS sequence based on atleast one of the full SRS bandwidth (e.g., SRS hopping bandwidth), theSRS bandwidth, the starting frequency position, the transmission comb,and/or one or more other parameters indicated in the SRS configurationinformation 622 a. The first UE 604 a may be configured (e.g.,preconfigured) with a function or other algorithm that takes one or moreof the aforementioned parameters as inputs, and returns the SRS sequenceas an output according to evaluation of the function/algorithm with theinput parameters.

While an SRS sequence may be generated based on the full SRS bandwidth,one of the UEs 604 a-b may be configured to truncate the SRS sequencewhen transmitting SRS on a partial SRS bandwidth. For example, the firstUE 604 a may generate an SRS sequence based on the full SRS bandwidthconfigured by the base station 602, but may refrain from mapping asubsequence of the SRS sequence to those resources (e.g., REs) outsideof the partial SRS bandwidth. The subsequence may map to part(s) of thefull SRS bandwidth outside of the partial SRS bandwidth over one or moreomitted symbol hops, whereas the truncated SRS sequence may be carriedon the part(s) of the full SRS bandwidth included in the partial SRSbandwidth over one or more other symbol hops.

In some other aspects, SRS sequence generation may be based on a partialSRS bandwidth, which may be indicated by at least one of SRSconfiguration information 622 a-b for at least one of the UEs 604 a-bthat supports SRS transmission on a partial SRS bandwidth. For example,the first UE 604 a may generate 624 an SRS sequence based on at leastthe partial SRS bandwidth, and potentially based further on at least oneof the full SRS bandwidth (e.g., SRS hopping bandwidth), the SRSbandwidth, the starting frequency position, the transmission comb,and/or one or more other parameters indicated in the SRS configurationinformation 622 a. The first UE 604 a may be configured (e.g.,preconfigured) with a function or other algorithm that takes at leastthe partial SRS bandwidth (e.g., number and/or position of RB(s)included in the partial SRS bandwidth) as an input, and returns the SRSsequence as an output according to evaluation of the function/algorithmwith the input parameters.

Potentially, not all UEs may support SRS transmission on a partial SRSbandwidth (e.g., some legacy UEs may lack such support). Therefore, atleast one cyclic shift may be used for an SRS sequence that is based onthe partial SRS bandwidth. The at least one cyclic shift may bedifferent from another cyclic shift used for another SRS sequence thatis based on the full SRS bandwidth—e.g., a different cyclic shift persubband may be used. Different cyclic shifts used for SRS transmissionson partial and full SRS bandwidths may reduce interference by UEstransmitting SRS on the partial SRS bandwidth to UEs transmitting SRS onthe full SRS bandwidth (e.g., legacy UEs).

In still other aspects, a new SRS sequence may be configured for use ona partial SRS bandwidth. When such a new SRS sequence is transmitted ona partial SRS bandwidth, the new SRS sequence may be orthogonal toanother SRS sequence generated based on (and transmitted on) the fullSRS bandwidth (e.g., legacy generation of an SRS sequence). For example,the first UE 604 a may generate 624 a new SRS sequence configured foruse on a partial SRS bandwidth that is less than a full SRS bandwidth.

In connection with generating a respective SRS sequence, each of the UEs604 a-b may determine 628, 630 a respective frequency hopping patternfor SRS transmission. At least one of the UEs 604 a-b may determine anSRS frequency hopping pattern for a partial SRS bandwidth that is lessthan a full SRS bandwidth. Further, a respective partial SRS bandwidthfrequency hopping pattern may be periodic, aperiodic, orsemi-persistent, e.g., as indicated according to one of the SRSconfiguration information 622 a-b. In some aspects, at least one of theUEs 604 a-b may determine 628, 630 a respective partial SRS bandwidthfrequency hopping pattern based at least in part on a respective one ofthe generated SRS sequences.

In some other aspects, the base station 602 may configure a respectiveSRS frequency hopping pattern for at least one of the UEs 604 a-b, andtherefore, at least one of the UEs 604 a-b may determine 628, 630 arespective SRS frequency hopping pattern according to the configurationreceived from the base station 602. For example, the base station 602may transmit, to each of the UEs 604 a-b, a respective one of SRSconfiguration information 622 a-b that indicates a partial bandwidth(e.g., number and position of RBs) on which to transmit an SRS resourceat each hop, with each hop occurring over one symbol of a set ofadjacent symbols.

In various further aspects, the base station 602 may implicitly indicatea respective SRS frequency hopping pattern to at least one of the UEs604 a-b. Accordingly, at least one of the UEs 604 a-b may determine(e.g., compute, derive, etc.) a respective bandwidth position (e.g.,starting frequency position, starting RB position, ending frequencyposition, etc.) corresponding to each symbol hop for SRS resourcetransmission.

In still additional aspects, at least one of the UEs 604 a-b maydetermine an SRS frequency hopping pattern for the full SRS bandwidth(e.g., based on a respective one of the SRS configuration information622 a-b). At least one of the UEs 604 a-b may then determine the partialSRS bandwidth frequency hopping pattern by determining a portion of theSRS transmission to be omitted. For example, at least one of the UEs 604a-b may determine a frequency hopping pattern for the full SRSbandwidth, but may subsequently determine the frequency hopping patternfor the partial SRS bandwidth by determining to refrain from SRStransmission on some portion of the full SRS bandwidth.

When determined, an SRS frequency hopping pattern for a partial SRSbandwidth may define, for SRS resource(s) of an SRS resource set, atleast one of: (1) a subset of a set of RBs per symbol (e.g., per hop) ofa set of symbols (e.g., a set of hops) for SRS transmission, and/or (2)a subset of the set of symbols for SRS transmission. In effect, at leastone of the UEs 604 a-b may refrain from transmitting SRS resource(s) onone or more RBs of at least one symbol hop of a partial SRS hoppingpattern and/or refrain from transmitting SRS resource(s) at one or moresymbol hops of a partial SRS hopping pattern (e.g., such that all RBs ofthe one or more symbol hops are skipped).

Referring to FIG. 8 , for example, a diagram 800 illustrates examplepartial SRS bandwidth frequency hopping patterns 802, 822, 842.According to the partial SRS bandwidth frequency hopping patterns 802,822, 842 of FIG. 8 , the frequency resources (e.g., RBs) of each hop maybe divided into N sub-resources (or “sub-hops”). Therefore, SRStransmission by one UE would occur on only one of the N sub-resourcesthat the resources of each hop is divided. For example, SRS transmissionby one UE would only occur on a subset of the set of 4× RBs per symbolhop. Effectively, hopping over each symbol hop may be viewed as an outerloop, and the partial SRS frequency hopping pattern may introduce aninner loop so that one UE only hops to one of the N sub-resources intowhich the resources of each symbol hop is divided. Potentially, thefrequency resources of each sub-hop (e.g., the N sub-resources) may begreater than 4 RBs or may be greater than or equal to 4 RBs (althoughother numbers of frequency resources are possible).

In some aspects, the ratio of sub-hop frequency resources to hopfrequency resources may be configured based on a threshold (e.g., apredefined threshold). For example, the ratio of sub-hop frequencyresources to hop frequency resources may be constrained to be within athreshold. Illustratively, the threshold may be equal to ½, and the basestation 602 may divide the 4× RBs of each hop into 4 sub-hops of 1 RBeach so that the ratio of sub-hop frequency resources to hop frequencyresources is ¼, which is within the threshold of ½.

According to some aspects shown by the first partial SRS bandwidthfrequency hopping pattern 802, each of the sub-hops of a symbol hopincludes the same number of resources—e.g., each sub-hop of a symbol hopincludes x RBs—and further, each of the hops has the same number ofsub-hops—e.g., each hop has 4 sub-hops. For example, each symbol hop mayinclude 4× RBs, where x may be equal to 4 or x may be greater than 4(although other values are possible). The 4× RBs of each symbol hop maybe divided into sub-hops of (4×)/(N) RBs—e.g., if N=4, then each hop maybe evenly divided into x RBs.

According to some other aspects shown by the second partial SRSbandwidth frequency hopping pattern 822, each of the sub-hops of asymbol hop includes the same number of resources—e.g., each sub-hop of asymbol hop includes x RBs— but each of the hops do not have the samenumber of sub-hops—e.g., hops at symbols 10 and 11 have 4 sub-hops,whereas hops as symbols 12 and 13 have 2 sub-hops. For example, eachsymbol hop may include 4× RBs, where x may be equal to 4 or x may begreater than 4 (although other values are possible). The 4× RBs of hopsat symbols 10 and 11 may be divided into sub-hops of (4×)/4 RBs or xRBs, whereas the 4× RBs of hops at symbols 12 and 13 may be divided intosub-hops of (4×)/2 RBs or 2× RBs.

According to still other aspects shown by the third partial SRSbandwidth frequency hopping pattern 842, each of the sub-hops of somesymbol hops include different numbers of resources—e.g., hops at symbols11 and 13 each include one sub-hop with 3× RBs and one sub-hop with xRBs—and, further, each of the hops do not have the same number ofsub-hops—e.g., hops at symbols 10 and 12 have 4 sub-hops, whereas hopsas symbols 11 and 13 have 2 sub-hops. For example, each symbol hop mayinclude 4× RBs, where x may be equal to 4 or x may be greater than 4(although other values are possible). The 4× RBs of hops at symbols 10and 12 may be divided into sub-hops of (4×)/4 RBs or x RBs, whereas the4× RBs of hops at symbols 11 and 13 may be divided into one sub-hop of4× RBs and another sub-hop of x RBs.

When at least one of the UEs 604 a-b is configured with a partial SRSbandwidth frequency hopping pattern that is limited to a subset of theset of RB s of at least one symbol hop for SRS transmission, the atleast one of the UEs 604 a-b may transmit SRS only on that subset of theset of RBs at that at least one symbol hop. Consequently, the at leastone of the UEs 604 a-b may refrain from transmitting SRS on other RBs ofa symbol hop not included in the subset of RBs.

For example, the first UE 604 a may be configured with an SRS resourceset including first SRS 804 a, and the second UE 604 b may be configuredwith an SRS resource set includes second SRS 804 b. Then, with one ofthe partial SRS bandwidth frequency hopping patterns 802, 822, 824, thefirst and second UEs 604 a-b may then only transmit respective SRS 804a-b on those RBs respectively configured for one of SRS 804 a-b persymbol hop.

Similarly, a third UE and a fourth UE may be configured to transmitthird SRS 804 c and fourth SRS 804 d, respectively, according to aconfigured one of the partial SRS bandwidth frequency hopping patterns802, 822, 842. Thus, multiple UEs (e.g., up to four UEs) may bemultiplexed at each symbol hop to sound over a partial SRS bandwidth.

The base station 602 may assign sub-hops of symbol hops to UEs for suchmultiplexing. Further, the base station 602 may configure the divisionof resources into sub-hops for each hop, and may assign resources ofeach sub-hop to one of the UEs 604 a-b. The base station 602 maytransmit such a resource assignment in the SRS configuration information622 a-b, e.g., via RRC signaling, DCI, and/or MAC CE.

Turning to FIG. 9 , as another example, a diagram 900 illustratesexample partial SRS bandwidth frequency hopping patterns 902, 922, 942.According to the partial SRS bandwidth frequency hopping patterns 902,922, 942 of FIG. 9 , the number of hops may be limited so that SRStransmission occurs only over a partial SRS bandwidth that is less thanthe full SRS bandwidth. When the number of symbol hops is limited, theUEs 604 a-b may still use the configured number of SRS symbols and hopsto determine 628, 630 the SRS frequency hopping pattern. However, theUEs 604 a-b may refrain from transmitting on a subset of the set ofsymbol hops.

In some aspects, a partial SRS bandwidth frequency hopping pattern mayinclude a limitation on a full SRS bandwidth frequency hopping pattern.The base station 602 may activate a respective limitation for each ofthe UEs 604 a-b that restricts the symbol hops on which each of the UEs604 a-b may transmit SRS 904 a-b. The base station 602 may transmit sucha limitation in the SRS configuration information 622 a-b, e.g., via RRCsignaling, DCI, and/or MAC CE.

For example, the limitation may be configured for each of the UEs 604a-b according to a skipping pattern that indicates the symbol hops onwhich each of the UEs 604 a-b is to transmit, and the other symbol hopson which each of the UEs 604 a-b is to refrain from transmitting. Forexample, the base station 602 may transmit a respective bitmap to eachof the UEs 604 a-b that indicates a respective skipping pattern.

Illustratively, the base station 602 may transmit a first bitmap to thefirst UE 604 a that indicates [1, 1, 0, 0], with a “1” indicating anassigned hop and a “0” indicating an unassigned hop. As shown in thefirst frequency hopping pattern 902, then, the first UE 604 a maytransmit SRS 904 a on the set of RBs of the first and second hops atsymbols 10 and 11, but may refrain from transmitting SRS on the thirdand fourth hops at symbols 12 and 13.

Similarly, the base station 602 may transmit a second bitmap to thesecond UE 604 b that indicates [0, 0, 1, 1]. As shown in the firstfrequency hopping pattern 902, then, the second UE 604 b may transmitSRS 904 b on the set of RBs of the third and fourth hops at symbols 12and 13, but may refrain from transmitting SRS on the first and secondhops at symbols 10 and 11.

In some aspects, the limitation (e.g., skipping pattern) may be periodicor cycling. For example, the base station 602 may configure a frequencyhopping pattern in which the first and second UEs 604 a-b aremultiplexed (e.g., as shown in patterns 902, 942), which may cycle witha frequency hopping pattern 922 in which only the first UE 604 atransmits SRS 904 a on all 4× RBs of all symbols hops (e.g., the secondUE 604 b refrains from SRS transmission).

Continuing with FIG. 10 , as a third example, a diagram 1000 illustratesexample partial SRS bandwidth frequency hopping patterns 1002, 1022.According to the partial SRS bandwidth frequency hopping patterns 1002,1022 of FIG. 10 , frequency hopping patterns in which the SRStransmission is limited to a subset of a set of RBs for at least onesymbol hop (e.g., as shown at FIG. 8 ) may be combined with frequencyhopping patterns in which the number of hops may be limited so that SRStransmission occurs only over a partial SRS bandwidth (e.g., as shown atFIG. 9 ).

For example, the base station 602 may configure a skipping pattern tolimit a frequency hopping pattern to some symbol hops and, potentially,those symbol hops activated for SRS transmission may be constrained to asubset of the set of RBs of those symbol hops. The base station 602 mayuse the same signaling or may use different signaling to inform the UEs604 a-b of the skipping pattern and the subset of RBs (e.g., sub-hops).Thus, each of the SRS configuration information 622 a-b may include oneor more messages indicating a respective skipping pattern and arespective subset of RBs for symbol hops for one of the UEs 604 a-b. Theone or more messages may be transmitted by the base station 602 via RRCsignaling, DCI, and/or MAC CE.

As shown in pattern 1002, the base station 602 may configure the firstUE 604 a to transmit SRS 1004 a on the first x RBs of the 4× RBs of eachsymbol hop that is activated. Similarly, the base station 602 mayconfigure the second UE 604 b to transmit SRS 1004 b on the second x RBsof the 4× RBs of each symbol hop that is activated. However, the basestation 602 may deactivate (or skip) the hops at symbols 11 and 13, andtherefore, neither the first UE 604 a nor the second UE 604 b maytransmit on any RBs of the hops at symbols 11 and 13.

In the pattern 1004, however, the base station 602 may configure thefirst UE 604 a to transmit SRS 1004 a on the first x RBs of the 4× RBsof hops at symbols 10 and 12. Similarly, the base station 602 mayconfigure the second UE 604 b to transmit SRS 1004 b on the second x RBsof the 4× RBs of hops at symbols 10 and 12. The base station 602 maydeactivate (or skip) the hops at symbols 11 and 13 for the second UE 604b, so that the frequency hopping pattern determined 630 by the second UE604 b causes the second UE 604 b to refrain from SRS transmission onhops at symbols 11 and 13. Conversely, the base station 602 may activatethe full hops at symbols 11 and 13 for the first UE 604 a, so that thefrequency hopping pattern determined 628 by the first UE 604 a causesthe first UE 604 a to transmit SRS 1004 a on hops at symbols 11 and 13.

The foregoing patterns described at FIGS. 8-10 are intended to beillustrative. Accordingly, other frequency hopping patterns may beconfigured according to the present disclosure.

According to the respectively determined 628, 630 frequency hoppingpatterns, the UEs 604 a-b may respectively transmit SRS 632, 634. Thetransmitted SRS 632, 634 may include the respectively generated 624, 626sequences. However, neither the first SRS 632 nor the second SRS 634 mayspan the full SRS bandwidth (e.g., SRS hopping bandwidth), but may spanonly a subset of the RBs at each symbol hop and/or may be absent fromone or more symbol hops of one or more slots.

FIG. 11 is a flowchart 1100 of a method of wireless communication. Themethod may be performed by a UE (e.g., the UE 104, 350, 604 a, 604 b).According to various aspects, one or more of the illustrated operationsmay be transposed, omitted, and/or contemporaneously performed.

At 1102, the UE may generate a sequence for SRS transmission based on atleast a portion of a full SRS bandwidth. In some aspects, the UE maygenerate a sequence based on a number of RBs of the full SRS bandwidth,and the UE may truncate the sequence for use in a partial SRS bandwidth.For example, the UE may assign a truncated portion of the sequence toeach of a subset of a set of symbols based on a frequency hoppingpattern such that SRS transmission includes each truncated portion ofthe sequence assigned to the subset of the set of symbols. In some otheraspects, the UE may generate the sequence based on a number of RBs of apartial SRS bandwidth that is less than the full SRS bandwidth, and SRStransmission may include the sequence. For example, the UE may generatethe sequence based on one or more cyclic shifts, and a number of the oneor more cyclic shifts may be based on the partial SRS bandwidth. Infurther aspects, the UE may generate a sequence that is orthogonal toeach overlapping sequence on the partial SRS bandwidth.

For example, referring to FIG. 6 , the first UE 604 a may generate 624 asequence for the SRS 632 and/or the second UE 604 b may generate 626 asequence for the SRS 634.

At 1104, the UE may receive, from a base station, SRS configurationinformation indicating at least a full SRS bandwidth. For example,referring to FIG. 6 , the first UE 604 a may receive, from the basestation 602, SRS configuration information 622 a indicating at least afull SRS bandwidth and/or the second UE 604 b may receive, from the basestation 602, SRS configuration information 622 b indicating at least afull SRS bandwidth.

At 1106, the UE may determine a frequency hopping pattern for SRStransmission based on the SRS configuration information, and thefrequency hopping pattern may be limited to a partial SRS bandwidth lessthan the full SRS bandwidth. For example, the SRS configurationinformation may further indicate a set of RBs per symbol of a set ofsymbols available for the SRS transmission, and the frequency hoppingpattern may be limited to at least one of a subset of the set of RBs persymbol or a subset of the set of symbols. In some aspects, the ratio ofthe subset of RBs to the set of RBs per symbol may be less than or equalto a threshold. In some other aspects, a respective subset of RBs persymbol is different for at least two of the set of symbols. In stillother aspects, the SRS configuration information further indicates thesubset of RBs assigned to the UE. In some further aspects, the SRSconfiguration indicates the subset of the set of symbols assigned to (oractivated for) the UE. In even further aspects, the SRS configurationincludes a bitmap having a first value corresponding to each of thesubset of the set of symbols assigned to the UE, and having a secondvalue corresponding to each remaining symbol of the set of symbolsunassigned to the UE.

For example, referring to FIG. 6 , the first UE 604 a may determine 628a frequency hopping pattern for SRS transmission based on the SRSconfiguration information 622 a, and the frequency hopping pattern maybe limited to a partial SRS bandwidth less than the full SRS bandwidth,and/or the second UE 604 b may determine 630 a frequency hopping patternfor SRS transmission based on the SRS configuration information 622 b,and the frequency hopping pattern may be limited to a partial SRSbandwidth less than the full SRS bandwidth. Referring to FIGS. 8-10 ,the first UE 604 a and/or the second UE 604 b may determine a frequencyhopping pattern that is one of frequency hopping patterns 802, 822, 842of FIG. 8 , one of frequency hopping patterns 902, 922, 942 of FIG. 9 ,and/or one of frequency hopping patterns 1002, 1022 of FIG. 10 .

At 1108, the UE may transmit the SRS transmission to the base stationbased on the frequency hopping pattern. The SRS transmission may includethe generated sequence, which may be truncated or may be a new sequencebased on the partial SRS bandwidth and/or orthogonal to other sequencesoverlapping on the partial SRS bandwidth.

For example, referring to FIG. 6 , the first UE 604 a may transmit theSRS 632 to the base station 602 based on the determined 628 frequencyhopping pattern, and/or the second UE 604 b may transmit the SRS 634 tothe base station 602 based on the determined 630 frequency hoppingpattern. Referring to FIGS. 8-10 , the first UE 604 a may transmit, tothe base station 602, SRS 804 a based on one of frequency hoppingpatterns 802, 822, 842 of FIG. 8 , SRS 904 a based on one of frequencyhopping patterns 902, 922, 942 of FIG. 9 , and/or SRS 1004 a based onone of frequency hopping patterns 1002, 1022 of FIG. 10 . Further toFIGS. 8-10 , the second UE 604 b may transmit, to the base station 602,SRS 804 b based on one of frequency hopping patterns 802, 822, 842 ofFIG. 8 , SRS 904 b based on one of frequency hopping patterns 902, 922,942 of FIG. 9 , and/or SRS 1004 b based on one of frequency hoppingpatterns 1002, 1022 of FIG. 10 .

FIG. 12 is a flowchart 1200 of a method of wireless communication. Themethod may be performed by a base station (e.g., the base station102/180, 310, 602). According to various aspects, one or more of theillustrated operations may be transposed, omitted, and/orcontemporaneously performed.

At 1202, the base station may transmit, to a UE, SRS configurationinformation indicating at least a full SRS bandwidth. For example,referring to FIG. 6 , the base station 602 may transmit, to the first UE604 a, SRS configuration information 622 a indicating at least a fullSRS bandwidth and/or may transmit, to the second UE 604 b, SRSconfiguration information 622 b indicating at least a full SRSbandwidth.

At 1204, the base station may receive, from the UE, an SRS transmissionaccording to a frequency hopping pattern based on the SRS configurationinformation, and the frequency hopping pattern may be limited to apartial SRS bandwidth less than the full SRS bandwidth. For example, theSRS configuration information may further indicate a set of RBs persymbol of a set of symbols available for the SRS transmission, and thefrequency hopping pattern may be limited to at least one of a subset ofthe set of RBs per symbol or a subset of the set of symbols. In someaspects, the ratio of the subset of RBs to the set of RBs per symbol maybe less than or equal to a threshold. In some other aspects, arespective subset of RBs per symbol is different for at least two of theset of symbols. In still other aspects, the SRS configurationinformation further indicates the subset of RBs assigned to the UE. Insome further aspects, the SRS configuration indicates the subset of theset of symbols assigned to (or activated for) the UE. In even furtheraspects, the SRS configuration includes a bitmap having a first valuecorresponding to each of the subset of the set of symbols assigned tothe UE, and having a second value corresponding to each remaining symbolof the set of symbols unassigned to the UE. In some aspects, the SRStransmission may include a set of truncated portions of a sequence thatis based on based on a number of RBs of the full SRS bandwidth. In someother aspects, the SRS transmission includes a sequence based on anumber of RBs of the partial SRS bandwidth. In still other aspects, thesequence is based on one or more cyclic shifts, and a number of the oneor more cyclic shifts may be based on the partial SRS bandwidth. Infurther aspects, the SRS transmission includes a sequence that isorthogonal to each overlapping sequence on the partial SRS bandwidth.

For example, referring to FIG. 6 , the base station 602 may receive,from the first UE 604 a, the SRS 632 according to a frequency hoppingpattern based on the SRS configuration information 622 a, and thefrequency hopping pattern may be limited to a partial SRS bandwidth lessthan the full SRS bandwidth. Referring to FIGS. 8-10 , the base station602 may receive, from the first UE 604 a, SRS 804 a according to one offrequency hopping patterns 802, 822, 842 of FIG. 8 based on the SRSconfiguration information 622 a, SRS 904 a according to one of frequencyhopping patterns 902, 922, 942 of FIG. 9 based on the SRS configurationinformation 622 a, and/or SRS 1004 a according to one of frequencyhopping patterns 1002, 1022 of FIG. 10 based on the SRS configurationinformation 622 a. Further, referring to FIG. 6 , the base station 602may receive, from the second UE 604 b, the SRS 634 according to afrequency hopping pattern based on the SRS configuration information 622b, and the frequency hopping pattern may be limited to a partial SRSbandwidth less than the full SRS bandwidth. Referring to FIGS. 8-10 ,the base station 602 may receive, from the second UE 604 b, SRS 804 baccording to one of frequency hopping patterns 802, 822, 842 of FIG. 8based on the SRS configuration information 622 b, SRS 904 b according toone of frequency hopping patterns 902, 922, 942 of FIG. 9 based on theSRS configuration information 622 b, and/or SRS 1004 b according to oneof frequency hopping patterns 1002, 1022 of FIG. 10 based on the SRSconfiguration information 622 b.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Terms such as “if,” “when,” and“while” should be interpreted to mean “under the condition that” ratherthan imply an immediate temporal relationship or reaction. That is,these phrases, e.g., “when,” do not imply an immediate action inresponse to or during the occurrence of an action, but simply imply thatif a condition is met then an action will occur, but without requiring aspecific or immediate time constraint for the action to occur. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects. Unless specifically stated otherwise, the term “some” refers toone or more. Combinations such as “at least one of A, B, or C,” “one ormore of A, B, or C,” “at least one of A, B, and C,” “one or more of A,B, and C,” and “A, B, C, or any combination thereof” include anycombination of A, B, and/or C, and may include multiples of A, multiplesof B, or multiples of C. Specifically, combinations such as “at leastone of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B,and C,” “one or more of A, B, and C,” and “A, B, C, or any combinationthereof” may be A only, B only, C only, A and B, A and C, B and C, or Aand B and C, where any such combinations may contain one or more memberor members of A, B, or C. All structural and functional equivalents tothe elements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. The words “module,”“mechanism,” “element,” “device,” and the like may not be a substitutefor the word “means.” As such, no claim element is to be construed as ameans plus function unless the element is expressly recited using thephrase “means for.”

What is claimed is:
 1. A method of wireless communication by a userequipment (UE), comprising: receiving, from a base station, soundingreference signal (SRS) configuration information indicating a full SRSbandwidth; determining a frequency hopping pattern for SRS transmissionbased on the SRS configuration information, the frequency hoppingpattern being limited to a partial SRS bandwidth less than the full SRSbandwidth; and transmitting the SRS transmission to the base stationbased on the frequency hopping pattern.
 2. The method of claim 1,wherein the SRS configuration information further indicates a set ofresource blocks (RBs) per symbol of a set of symbols available for theSRS transmission, and the frequency hopping pattern is limited to atleast one of a subset of the set of RBs per symbol or a subset of theset of symbols.
 3. The method of claim 2, wherein a ratio of the subsetof RBs to the set of RBs per symbol is less than or equal to athreshold.
 4. The method of claim 2, wherein a respective subset of RBsper symbol is different for at least two of the set of symbols.
 5. Themethod of claim 2, wherein the SRS configuration information furtherindicates the subset of RBs assigned to the UE.
 6. The method of claim2, wherein the SRS configuration information indicates the subset of theset of symbols assigned to the UE.
 7. The method of claim 6, wherein theSRS configuration information comprises a bitmap having a first valuecorresponding to each of the subset of the set of symbols assigned tothe UE and a second value corresponding to each remaining symbol of theset of symbols unassigned to the UE.
 8. The method of claim 2, furthercomprising: generating a sequence based on a number of RBs of the fullSRS bandwidth; and assigning a truncated portion of the sequence to eachof the subset of the set of symbols, wherein the SRS transmissioncomprises each truncated portion of the sequence assigned to the subsetof the set of symbols.
 9. The method of claim 1, further comprising:generating a sequence based on a number of RBs of the partial SRSbandwidth, wherein the SRS transmission comprises the sequence.
 10. Themethod of claim 9, wherein the sequence is generated based on one ormore cyclic shifts, a number of the one or more cyclic shifts beingbased on the partial SRS bandwidth.
 11. The method of claim 1, whereinthe SRS transmission comprises a sequence that is orthogonal to eachoverlapping sequence on the partial SRS bandwidth.
 12. A method ofwireless communication by a base station, comprising: transmitting, to auser equipment (UE), sounding reference signal (SRS) configurationinformation indicating a full SRS bandwidth; receiving, from the UE, anSRS transmission according to a frequency hopping pattern based on theSRS configuration information, the frequency hopping pattern beinglimited to a partial SRS bandwidth less than the full SRS bandwidth. 13.The method of claim 12, wherein the SRS configuration informationfurther indicates a set of resource blocks (RBs) per symbol of a set ofsymbols available for SRS transmission, and the frequency hoppingpattern is limited to at least one of a subset of the set of RBs persymbol or a subset of the set of symbols.
 14. The method of claim 13,wherein a ratio of the subset of RBs to the set of RBs per symbol isless than or equal to a threshold.
 15. The method of claim 13, wherein arespective subset of RBs per symbol is different for at least two of theset of symbols.
 16. The method of claim 13, wherein the SRSconfiguration information further indicates the subset of RBs assignedto the UE.
 17. The method of claim 13, wherein the SRS configurationinformation indicates the subset of the set of symbols assigned to theUE.
 18. The method of claim 17, wherein the SRS configurationinformation comprises a bitmap having a first value corresponding toeach of the subset of the set of symbols assigned to the UE and a secondvalue corresponding to each remaining symbol of the set of symbolsunassigned to the UE.
 19. The method of claim 13, further comprising,wherein the SRS transmission comprises a set of truncated portions of asequence that is based on based on a number of RBs of the full SRSbandwidth.
 20. The method of claim 12, wherein the SRS transmissioncomprises a sequence based on a number of RBs of the partial SRSbandwidth.
 21. The method of claim 20, wherein the sequence is based onone or more cyclic shifts, a number of the one or more cyclic shiftsbeing based on the partial SRS bandwidth.
 22. The method of claim 12,wherein the SRS transmission comprises a sequence that is orthogonal toeach overlapping sequence on the partial SRS bandwidth.
 23. An apparatusfor wireless communication by a user equipment (UE), comprising: amemory; and at least one processor coupled to the memory and configuredto: receive, from a base station, sounding reference signal (SRS)configuration information indicating a full SRS bandwidth; determine afrequency hopping pattern for SRS transmission based on the SRSconfiguration information, the frequency hopping pattern being limitedto a partial SRS bandwidth less than the full SRS bandwidth; andtransmit the SRS transmission to the base station based on the frequencyhopping pattern.
 24. The apparatus of claim 23, wherein the SRSconfiguration information further indicates a set of resource blocks(RBs) per symbol of a set of symbols available for the SRS transmission,and the frequency hopping pattern is limited to at least one of a subsetof the set of RBs per symbol or a subset of the set of symbols.
 25. Theapparatus of claim 24, wherein a ratio of the subset of RBs to the setof RBs per symbol is less than or equal to a threshold.
 26. Theapparatus of claim 24, wherein a respective subset of RBs per symbol isdifferent for at least two of the set of symbols.
 27. The apparatus ofclaim 24, wherein the SRS configuration information further indicatesthe subset of RBs assigned to the UE.
 28. The apparatus of claim 24,wherein the SRS configuration information indicates the subset of theset of symbols assigned to the UE.
 29. The apparatus of claim 28,wherein the SRS configuration information comprises a bitmap having afirst value corresponding to each of the subset of the set of symbolsassigned to the UE and a second value corresponding to each remainingsymbol of the set of symbols unassigned to the UE.
 30. The apparatus ofclaim 24, wherein the at least one processor is further configured to:generate a sequence based on a number of RBs of the full SRS bandwidth;and assign a truncated portion of the sequence to each of the subset ofthe set of symbols, wherein the SRS transmission comprises eachtruncated portion of the sequence assigned to the subset of the set ofsymbols.
 31. The apparatus of claim 23, wherein the at least oneprocessor is further configured to: generate a sequence based on anumber of RBs of the partial SRS bandwidth, wherein the SRS transmissioncomprises the sequence.
 32. The apparatus of claim 31, wherein thesequence is generated based on one or more cyclic shifts, a number ofthe one or more cyclic shifts being based on the partial SRS bandwidth.33. The apparatus of claim 23, wherein the SRS transmission comprises asequence that is orthogonal to each overlapping sequence on the partialSRS bandwidth.
 34. An apparatus of wireless communication by a basestation, comprising: a memory; and at least one processor coupled to thememory and configured to: transmit, to a user equipment (UE), soundingreference signal (SRS) configuration information indicating a full SRSbandwidth; receive, from the UE, an SRS transmission according to afrequency hopping pattern based on the SRS configuration information,the frequency hopping pattern being limited to a partial SRS bandwidthless than the full SRS bandwidth.
 35. The apparatus of claim 34, whereinthe SRS configuration information further indicates a set of resourceblocks (RBs) per symbol of a set of symbols available for SRStransmission, and the frequency hopping pattern is limited to at leastone of a subset of the set of RBs per symbol or a subset of the set ofsymbols.
 36. The apparatus of claim 35, wherein a ratio of the subset ofRBs to the set of RBs per symbol is less than or equal to a threshold.37. The apparatus of claim 35, wherein a respective subset of RBs persymbol is different for at least two of the set of symbols.
 38. Theapparatus of claim 35, wherein the SRS configuration information furtherindicates the subset of RBs assigned to the UE.
 39. The apparatus ofclaim 35, wherein the SRS configuration information indicates the subsetof the set of symbols assigned to the UE.
 40. The apparatus of claim 39,wherein the SRS configuration information comprises a bitmap having afirst value corresponding to each of the subset of the set of symbolsassigned to the UE and a second value corresponding to each remainingsymbol of the set of symbols unassigned to the UE.
 41. The apparatus ofclaim 35, wherein the at least one processor is further configured to,wherein the SRS transmission comprises a set of truncated portions of asequence that is based on based on a number of RBs of the full SRSbandwidth.
 42. The apparatus of claim 34, wherein the SRS transmissioncomprises a sequence based on a number of RBs of the partial SRSbandwidth.
 43. The apparatus of claim 42, wherein the sequence is basedon one or more cyclic shifts, a number of the one or more cyclic shiftsbeing based on the partial SRS bandwidth.
 44. The apparatus of claim 34,wherein the SRS transmission comprises a sequence that is orthogonal toeach overlapping sequence on the partial SRS bandwidth.
 45. An apparatusfor wireless communication by a user equipment (UE), comprising: meansfor receiving, from a base station, sounding reference signal (SRS)configuration information indicating a full SRS bandwidth; means fordetermining a frequency hopping pattern for SRS transmission based onthe SRS configuration information, the frequency hopping pattern beinglimited to a partial SRS bandwidth less than the full SRS bandwidth; andmeans for transmitting the SRS transmission to the base station based onthe frequency hopping pattern.
 46. The apparatus of claim 45, whereinthe SRS configuration information further indicates a set of resourceblocks (RBs) per symbol of a set of symbols available for the SRStransmission, and the frequency hopping pattern is limited to at leastone of a subset of the set of RBs per symbol or a subset of the set ofsymbols.
 47. The apparatus of claim 46, wherein a ratio of the subset ofRBs to the set of RBs per symbol is less than or equal to a threshold.48. The apparatus of claim 46, wherein a respective subset of RBs persymbol is different for at least two of the set of symbols.
 49. Theapparatus of claim 46, wherein the SRS configuration information furtherindicates the subset of RBs assigned to the UE.
 50. The apparatus ofclaim 46, wherein the SRS configuration information indicates the subsetof the set of symbols assigned to the UE.
 51. The apparatus of claim 50,wherein the SRS configuration information comprises a bitmap having afirst value corresponding to each of the subset of the set of symbolsassigned to the UE and a second value corresponding to each remainingsymbol of the set of symbols unassigned to the UE.
 52. The apparatus ofclaim 46, further comprising: means for generating a sequence based on anumber of RBs of the full SRS bandwidth; and means for assigning atruncated portion of the sequence to each of the subset of the set ofsymbols, wherein the SRS transmission comprises each truncated portionof the sequence assigned to the subset of the set of symbols.
 53. Theapparatus of claim 45, further comprising: means for generating asequence based on a number of RBs of the partial SRS bandwidth, whereinthe SRS transmission comprises the sequence.
 54. The apparatus of claim53, wherein the sequence is generated based on one or more cyclicshifts, a number of the one or more cyclic shifts being based on thepartial SRS bandwidth.
 55. The apparatus of claim 45, wherein the SRStransmission comprises a sequence that is orthogonal to each overlappingsequence on the partial SRS bandwidth.
 56. An apparatus of wirelesscommunication by a base station, comprising: means for transmitting, toa user equipment (UE), sounding reference signal (SRS) configurationinformation indicating a full SRS bandwidth; means for receiving, fromthe UE, an SRS transmission according to a frequency hopping patternbased on the SRS configuration information, the frequency hoppingpattern being limited to a partial SRS bandwidth less than the full SRSbandwidth.
 57. The apparatus of claim 56, wherein the SRS configurationinformation further indicates a set of resource blocks (RBs) per symbolof a set of symbols available for SRS transmission, and the frequencyhopping pattern is limited to at least one of a subset of the set of RBsper symbol or a subset of the set of symbols.
 58. The apparatus of claim57, wherein a ratio of the subset of RBs to the set of RBs per symbol isless than or equal to a threshold.
 59. The apparatus of claim 57,wherein a respective subset of RBs per symbol is different for at leasttwo of the set of symbols.
 60. The apparatus of claim 57, wherein theSRS configuration information further indicates the subset of RBsassigned to the UE.
 61. The apparatus of claim 57, wherein the SRSconfiguration information indicates the subset of the set of symbolsassigned to the UE.
 62. The apparatus of claim 61, wherein the SRSconfiguration information comprises a bitmap having a first valuecorresponding to each of the subset of the set of symbols assigned tothe UE and a second value corresponding to each remaining symbol of theset of symbols unassigned to the UE.
 63. The apparatus of claim 57,further comprising, wherein the SRS transmission comprises a set oftruncated portions of a sequence that is based on based on a number ofRBs of the full SRS bandwidth.
 64. The apparatus of claim 56, whereinthe SRS transmission comprises a sequence based on a number of RBs ofthe partial SRS bandwidth.
 65. The apparatus of claim 64, wherein thesequence is based on one or more cyclic shifts, a number of the one ormore cyclic shifts being based on the partial SRS bandwidth.
 66. Theapparatus of claim 56, wherein the SRS transmission comprises a sequencethat is orthogonal to each overlapping sequence on the partial SRSbandwidth.
 67. A computer-readable medium storing computer-executablecode for wireless communication by a user equipment (UE), the code whenexecuted by a processor cause the processor to: receive, from a basestation, sounding reference signal (SRS) configuration informationindicating a full SRS bandwidth; determine a frequency hopping patternfor SRS transmission based on the SRS configuration information, thefrequency hopping pattern being limited to a partial SRS bandwidth lessthan the full SRS bandwidth; and transmit the SRS transmission to thebase station based on the frequency hopping pattern.
 68. Acomputer-readable medium storing computer-executable code for wirelesscommunication by a base station, the code when executed by a processorcause the processor to: transmit, to a user equipment (UE), soundingreference signal (SRS) configuration information indicating a full SRSbandwidth; receive, from the UE, an SRS transmission according to afrequency hopping pattern based on the SRS configuration information,the frequency hopping pattern being limited to a partial SRS bandwidthless than the full SRS bandwidth.